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Fri Oct 03, 2008 4:40 pm

spoon wrote: architect_7 wrote: spoon wrote: Mike Fisher wrote: Maybe you need to adjust your MAPS like mad97321 was telling us all yesterday?

Okay. Just unbolted the ol' MAPS and had a looksie. The hose that connected the MAPS to the intake air distributor was a bit corroded at one end. The hose seemed to slip off quite easily from both nipples, especially the one under teh IAD. I cleaned her up and affixed a new, tighter fitting hose. I checked if she holds suction and she does, without any hissing.

I remounted the MAPS and the amount of white smoke seems to have declined. During idle, smoke is barely noticeable, yet the motor is still running rough. When revving, black smoke is now appearing from the tailpipes.

Also, here's a rundown on what happens when I remove...

Spark plug wire:
#1: Drop in RPM
#2: Drop in RPM
#3: Drop in RPM
#4: RPMs seem to stay the same, maybe

Injector lead:
#1: Drop in RPM
#2: Drop in RPM
#3: Drop in RPM
#4: RPMs seem to stay the same, maybe

This is exactly what I had trouble with. Replace number four injector, and be careful of its tip. I had one where I just bumped the tip, and because of this, the needle valve did not fully close, which caused the problem you are having. You can carefully press on the needle, and it should move about a millimeter. You can do this installed, and see it squirt some.

With the 3/4 injector pair removed from the head (but still connected to fuel lines) they are both holding fuel. No drops. Both needles are not protruding from the tip, they are flush with the tip. I took a paperclip and with the fuel system pressurized, and pressed both needles in, one at a time, and got what looked to be a cone-shaped spray. They made a "psst" sound. The number 4 injector is black-tipped, while the number 3 is yellow-tipped. How can I make positively sure that the number 4 injector is bad?

Although there is no more white smoke coming from the tailpipe, is it possible that my sparkplugs are now FOULED due to all of the troubleshooting?

That is a thought. I had forgotten about that. I.I.R.C., black is the correct, but one should check the number on the housing. They should be 001 or 007.

How about running cleaner in a tankful, and cleaning the spark plugs, and see if that helps.

Fri Oct 03, 2008 6:07 pm

My next move is to fill the tank up with some cleaner (I've already replaced the fuel filter a couple of times thinking it was the problem) and toss in some new plugs (W8AC's). If my ride don't ackrite after this, my buddy says he has not one, but TWO carb'd (eww!) pancake motors just sittin' in his garage. Oh and I pulled out the sending unit to have a looksie at the bottom of the gas tank. It looks like bare metal and I can see a few floaties in there, but there is nothing blocking or clogging the strainer. Any other suggestions?

Fri Oct 03, 2008 9:11 pm

For the record, I am not even THINKING about going carb'd!

Fri Oct 03, 2008 9:54 pm

It's also possible that there's an air leak at that injector, or at the intake manifold gasket at that cylinder.

Sat Oct 04, 2008 12:40 pm

Tram wrote: It's also possible that there's an air leak at that injector, or at the intake manifold gasket at that cylinder.

Really? Are there tell-tale signs other than my current symptoms that would indicate this?

Sat Oct 04, 2008 2:24 pm

spoon wrote: Tram wrote: It's also possible that there's an air leak at that injector, or at the intake manifold gasket at that cylinder.

Really? Are there tell-tale signs other than my current symptoms that would indicate this?

That cylinder will run perceptibly cooler than the others at idle is one sign.

Sat Oct 04, 2008 6:47 pm

Tram wrote: spoon wrote: Tram wrote: It's also possible that there's an air leak at that injector, or at the intake manifold gasket at that cylinder.

Really? Are there tell-tale signs other than my current symptoms that would indicate this?

That cylinder will run perceptibly cooler than the others at idle is one sign.

a-HAH! I can finally put my infrared thermo-meter to good use! I am away from my car for the weekend but I'll get back to ya'wle (sp?) with my findings on Monday. One question... how would the pseudo one bad cylinder cause the other sparkplugs to foul as well?

Sat Oct 04, 2008 7:47 pm

spoon wrote: Tram wrote: spoon wrote: Tram wrote: It's also possible that there's an air leak at that injector, or at the intake manifold gasket at that cylinder.

Really? Are there tell-tale signs other than my current symptoms that would indicate this?

That cylinder will run perceptibly cooler than the others at idle is one sign.

a-HAH! I can finally put my infrared thermo-meter to good use! I am away from my car for the weekend but I'll get back to ya'wle (sp?) with my findings on Monday. One question... how would the pseudo one bad cylinder cause the other sparkplugs to foul as well?

It's a vacuum leak. Vacuum leaks tend to make the D-Jet system run rich.

Sun Oct 05, 2008 5:02 pm

I got the Squareback on the road, and it surges ever so slightly when first starting out. The worst is it lacks power, and is terrible on hills. Valves were done about 1,000 miles, or less, and timing is dead on, throughout the range. I fixed the A.A.R., and the revolutions seem fine. New injectors on the one/two side, which seems to be a touch hotter.

Sun Oct 05, 2008 5:23 pm

architect_7 wrote: I got the Squareback on the road, and it surges ever so slightly when first starting out. The worst is it lacks power, and is terrible on hills. Valves were done about 1,000 miles, or less, and timing is dead on, throughout the range. I fixed the A.A.R., and the revolutions seem fine. New injectors on the one/two side, which seems to be a touch hotter.

annnnd so it looks like you've merged your problem along with onerase and mine. its freakin weird.

Sun Oct 05, 2008 5:26 pm

JSMskater wrote: architect_7 wrote: I got the Squareback on the road, and it surges ever so slightly when first starting out. The worst is it lacks power, and is terrible on hills. Valves were done about 1,000 miles, or less, and timing is dead on, throughout the range. I fixed the A.A.R., and the revolutions seem fine. New injectors on the one/two side, which seems to be a touch hotter.

annnnd so it looks like you've merged your problem along with onerase and mine. its freakin weird.

What is even more so is my Father;s is doing it also, and it is a '84 Chevy.

I do not like staying in first, which is how much power I lack (about 25 M.P.H., and a 40 percent grade). Is that the case for you?

Wed Oct 08, 2008 1:01 pm

Tram wrote: It's a vacuum leak. Vacuum leaks tend to make the D-Jet system run rich.

I really don't know where to start on this vacuum leak. I don't know what exactly should have vacuum, or even if the vacuum hoses already there are even in the right places. Can you post some sort of diagram that maps out all vacuum hoses and their connections? Now that'd be a sticky! 8)

Wed Oct 08, 2008 1:13 pm

spoon wrote: My next move is to fill the tank up with some cleaner (I've already replaced the fuel filter a couple of times thinking it was the problem) and toss in some new plugs (W8AC's). If my ride don't ackrite after this, my buddy says he has not one, but TWO carb'd (eww!) pancake motors just sittin' in his garage. Oh and I pulled out the sending unit to have a looksie at the bottom of the gas tank. It looks like bare metal and I can see a few floaties in there, but there is nothing blocking or clogging the strainer. Any other suggestions? Did you "toss in some new plugs (W8AC's)"? :wink:

Wed Oct 08, 2008 2:34 pm

spoon wrote: I really don't know where to start on this vacuum leak. I don't know what exactly should have vacuum, or even if the vacuum hoses already there are even in the right places. Can you post some sort of diagram that maps out all vacuum hoses and their connections? Now that'd be a sticky! 8)

In '69 hoses were simple:
Medium hose from IAD to MPS
Medium hose from IAD to pressure switch
Medium hose from IAD to AAR
Small hose from IAD to distributor advance
Four large hoses from IAD to intake runners

Also check the little rubber donuts on the injector tips, and the seal between the runners and the head (bakelite plate)

There are other hoses but leaks elsewhere will not confuse the EFI.

Wed Oct 08, 2008 2:54 pm

KTPhil wrote: spoon wrote: I really don't know where to start on this vacuum leak. I don't know what exactly should have vacuum, or even if the vacuum hoses already there are even in the right places. Can you post some sort of diagram that maps out all vacuum hoses and their connections? Now that'd be a sticky! 8)

In '69 hoses were simple:
Medium hose from IAD to MPS
Medium hose from IAD to pressure switch
Medium hose from IAD to AAR
Small hose from IAD to distributor advance
Four large hoses from IAD to intake runners

Also check the little rubber donuts on the injector tips, and the seal between the runners and the head (bakelite plate)

There are other hoses but leaks elsewhere will not confuse the EFI.

The little rubber donuts on the injector tips are all cracked up and really close to crumbling apart. Those have been ordered. As for the bakelite plate, I never looked at that and I will make sure to.

Wed Oct 08, 2008 3:04 pm

The plate leaks either becauase someone used the Bug metal plates instead of the thick bakelite ones, or they didn't use a paper gasket (I add a smear of sealant), or they put them on crooked and didn't torque them carefully. Some spray stuff (carb cleaner or other VOCs) and see if the idle speed changes to check for leaks there.

Wed Oct 08, 2008 3:28 pm

Just to clarify: I'm saying that he most likely has a vacuum leak on that one cylinder, which would mean failure of the connecting collar, injector seals, or manifold gasket. If the injector rubber rings are crumbling to dust, that could indeed be the issue.

Wed Oct 08, 2008 8:31 pm

Those little buggers are really important. If they leak, they add air to THAT cylinder, even as the others may run rich due to the vacuum leak confusing the MPS. So while it may seem to run a little rich (normally fairly harmless), it could be masking the fact that you could be burning up a valve in one cylinder due to leanness.

Thu Oct 09, 2008 8:47 am

So, after Spoon, can I get some help? I am not going to be able to work on it this weekend, but I would still like to think about it.

I was thinking what has been changed since the change in performance. It has been the injectors, A.A.R., and idle. Injectors have brand new seals, and did not seat well. I did not want to over tighten the nuts, so now I wonder if I should. Next, I should check the timing, because I might have bumped the distributor installing the A.A.R.. If this does not improve things, then I might try adjusting the idle.

Thu Oct 09, 2008 8:56 am

Drill a hole in your MAPS and adjust it!